An Economy Has Government Purchases of 2000

An economy has government purchases of 2000.Desired national saving and desired investment are given by S^d = 200 + 5000r + 0.10Y - 0.20G
I^d = 1000 - 4000r
When the full-employment level of output equals 5000,then the level of investment when the goods market is in equilibrium will be

A) 66.8.
B) 422.4.
C) 600.0.
D) 688.9.